wasm: move user configurable settings

Both INITIAL_MEMORY and PTHREAD_POOL_SIZE are settings users can
change, they are not interface settings.

Fixes: QTBUG-100693
Pick-to: 6.3 6.2
Change-Id: Ie1547c7f52c9fe109a313260616705728024b6b8
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: David Skoland <david.skoland@qt.io>

4 files changed, 83 insertions, 25 deletions

diff --git a/cmake/QtWasmHelpers.cmake b/cmake/QtWasmHelpers.cmake
index a494725d7d..47af621861 100644
--- a/cmake/QtWasmHelpers.cmake
+++ b/cmake/QtWasmHelpers.cmake
@@ -22,23 +22,6 @@ function (qt_internal_setup_wasm_target_properties wasmTarget)
         target_compile_options("${wasmTarget}" INTERFACE -O2 -msimd128 -msse -msse2)
     endif()
 
-    # Hardcode wasm memory size. Emscripten does not currently support memory growth
-    # (ALLOW_MEMORY_GROWTH) in pthreads mode, and requires specifying the memory size
-    # at build time. Further, browsers limit the maximum initial memory size to 1GB.
-    # QT_WASM_INITIAL_MEMORY must be a multiple of 64KB (i.e. 65536)
-    if(NOT DEFINED QT_WASM_INITIAL_MEMORY)
-        if(QT_FEATURE_thread)
-            set(QT_WASM_INITIAL_MEMORY "1GB")
-        else()
-            set(QT_WASM_INITIAL_MEMORY "20MB") # emscripten default is 16MB, we need slightly more sometimes
-        endif()
-    endif()
-
-    if(DEFINED QT_WASM_INITIAL_MEMORY)
-        target_link_options("${wasmTarget}" INTERFACE "SHELL:-s INITIAL_MEMORY=${QT_WASM_INITIAL_MEMORY}")
-        message("Setting INITIAL_MEMORY to ${QT_WASM_INITIAL_MEMORY}")
-    endif()
-
     if (QT_FEATURE_opengles3)
         target_link_options("${wasmTarget}" INTERFACE "SHELL:-s FULL_ES3=1")
 
@@ -58,14 +41,6 @@ function (qt_internal_setup_wasm_target_properties wasmTarget)
     if (QT_FEATURE_thread)
         target_compile_options("${wasmTarget}" INTERFACE "SHELL:-pthread")
         target_link_options("${wasmTarget}" INTERFACE "SHELL:-pthread")
-
-        set(POOL_SIZE 4)
-        if(DEFINED QT_WASM_PTHREAD_POOL_SIZE)
-            set(POOL_SIZE ${QT_WASM_PTHREAD_POOL_SIZE})
-        endif()
-        target_link_options("${wasmTarget}" INTERFACE "SHELL:-s PTHREAD_POOL_SIZE=${POOL_SIZE}")
-        message("Setting PTHREAD_POOL_SIZE to ${POOL_SIZE}")
-
     else()
         target_link_options("${wasmTarget}" INTERFACE "SHELL:-s ALLOW_MEMORY_GROWTH=1")
     endif()
diff --git a/doc/global/macros.qdocconf b/doc/global/macros.qdocconf
index 37c5a3ea1c..31cecc1b78 100644
--- a/doc/global/macros.qdocconf
+++ b/doc/global/macros.qdocconf
@@ -83,3 +83,5 @@ macro.cmakepropertyandroidonly = "\\note This property is used only if targeting
 macro.cmakevariableandroidonly = "\\note This variable is used only if targeting the Android platform."
 
 macro.versionlessCMakeCommandsNote = "If \\l{Versionless commands}{versionless commands} are disabled, use \\c{\1} instead. It supports the same set of arguments as this command."
+
+macro.cmakepropertywebassemblyonly = "\\note This property is used only if targeting the WebAssembly platform."
diff --git a/src/corelib/Qt6WasmMacros.cmake b/src/corelib/Qt6WasmMacros.cmake
index 2c915b3903..86044d7e02 100644
--- a/src/corelib/Qt6WasmMacros.cmake
+++ b/src/corelib/Qt6WasmMacros.cmake
@@ -18,5 +18,40 @@ function(_qt_internal_wasm_add_target_helpers target)
         configure_file("${WASM_BUILD_DIR}/plugins/platforms/qtlogo.svg"
             qtlogo.svg COPYONLY)
 
+        if(QT_FEATURE_thread)
+            set(POOL_SIZE 4)
+            get_target_property(_tmp_poolSize "${target}" QT_WASM_PTHREAD_POOL_SIZE)
+            if(_tmp_poolSize)
+                set(POOL_SIZE ${_tmp_poolSize})
+            elseif(DEFINED QT_WASM_PTHREAD_POOL_SIZE)
+                set(POOL_SIZE ${QT_WASM_PTHREAD_POOL_SIZE})
+            endif()
+            target_link_options("${target}" PRIVATE "SHELL:-s PTHREAD_POOL_SIZE=${POOL_SIZE}")
+            message(DEBUG "Setting PTHREAD_POOL_SIZE to ${POOL_SIZE} for ${target}")
+        endif()
+
+        # Hardcode wasm memory size. Emscripten does not currently support memory growth
+        # (ALLOW_MEMORY_GROWTH) in pthreads mode, and requires specifying the memory size
+        # at build time. Further, browsers limit the maximum initial memory size to 1GB.
+        # QT_WASM_INITIAL_MEMORY must be a multiple of 64KB (i.e. 65536)
+        get_target_property(_tmp_initialMemory "${target}" QT_WASM_INITIAL_MEMORY)
+        if(_tmp_initialMemory)
+            set(QT_WASM_INITIAL_MEMORY "${_tmp_initialMemory}")
+        elseif(NOT DEFINED QT_WASM_INITIAL_MEMORY)
+            if(QT_FEATURE_thread)
+                set(QT_WASM_INITIAL_MEMORY "1GB")
+            else()
+                # emscripten default is 16MB, we need slightly more sometimes
+                set(QT_WASM_INITIAL_MEMORY "20MB")
+            endif()
+        endif()
+
+        if(DEFINED QT_WASM_INITIAL_MEMORY)
+            target_link_options("${target}"
+                PRIVATE "SHELL:-s INITIAL_MEMORY=${QT_WASM_INITIAL_MEMORY}")
+            message(DEBUG "-- Setting INITIAL_MEMORY to ${QT_WASM_INITIAL_MEMORY} for ${target}")
+        endif()
+
     endif()
 endfunction()
+
diff --git a/src/corelib/doc/src/cmake/cmake-properties.qdoc b/src/corelib/doc/src/cmake/cmake-properties.qdoc
index 859b3e79af..347699736d 100644
--- a/src/corelib/doc/src/cmake/cmake-properties.qdoc
+++ b/src/corelib/doc/src/cmake/cmake-properties.qdoc
@@ -384,3 +384,49 @@ the property value overrides the runtime path where the resource file is found.
 
 \sa{The Qt Resource System}
 */
+
+/*!
+\page cmake-target-property-QT_WASM_PTHREAD_POOL_SIZE.html
+\ingroup cmake-properties-qtcore
+\ingroup cmake-target-properties-qtcore
+
+\title QT_WASM_PTHREAD_POOL_SIZE
+\target cmake-target-property-QT_WASM_PTHREAD_POOL_SIZE
+
+\summary {Internal WebAssembly thread pool size.}
+
+\cmakepropertysince 6.2.4
+\preliminarycmakeproperty
+\cmakepropertywebassemblyonly
+
+Specifies the number of web workers (threads) to create at application startup.
+Qt allocates a pool size of 4 by default. This means the app can use
+4 additional threads besides the main thread, without the additional overhead
+of creating a new web worker, which may deadlock if the main thread created it
+and join()s the thread without returning control to the event loop first.
+Translates into the Emscripten compiler setting of PTHREAD_POOL_SIZE.
+
+For more information, see \l{https://emscripten.org/docs/porting/pthreads.html}{Pthreads support}.
+*/
+
+/*!
+\page cmake-target-property-QT_WASM_INITIAL_MEMORY.html
+\ingroup cmake-properties-qtcore
+\ingroup cmake-target-properties-qtcore
+
+\title QT_WASM_INITIAL_MEMORY
+\target cmake-target-property-QT_WASM_INITIAL_MEMORY
+
+\summary {Internal WebAssembly initial memory.}
+
+\cmakepropertysince 6.2.4
+\preliminarycmakeproperty
+\cmakepropertywebassemblyonly
+
+Specifies the initial amount of memory to use, in bytes. Using more will cause the
+browser to copy the old heap into a new one. Translates into the
+Emscripten compiler setting of INITIAL_MEMORY.
+QT_WASM_INITIAL_MEMORY must be a multiple of 65536 bytes.
+
+For more information, see \l{https://github.com/emscripten-core/emscripten/blob/main/src/settings.js}{Emscripten compiler settings}.
+*/